The present invention relates generally to an image recording apparatus, such as a copying machine, and more particularly to an image recording apparatus in which a density of a reproduced image can be adjusted.
Various types of image recording apparatuses have been known and used in the art. One typical apparatus includes a light source for emitting a light toward the image face of an original. A photosensitive recording medium is disposed in a position where the light reflected upon or transmitted through the original is irradiated thereonto, so that the image of the original is recorded on the recording medium. More specifically, the light source and an original support pane on which the original is placed are moved relative to each other, and the light reflected from or transmitted through the original is irradiated through an optical system onto the photosensitive recording medium. A latent image is therefore formed on the recording medium, which is then developed and transferred to an image receiving sheet so that a visible image is provided thereon.
In such a recording apparatus, it has been required that the density of the image formed on the image receiving sheet be adjusted as desired, and this can be accomplished by manipulating a density adjusting switch provided on a panel. The output of the switch is applied to a light amount control unit for controlling an amount of light emitted from the light source, so that the amount of light emitted therefrom is controlled in response to the signal outputted from the density adjusting switch. In this manner, the amount of light reflected from or transmitted through the original has been controlled so that an amount of light applied to the recording media is changed to change the density of the visible image.
However, when recording mediums low in sensitivity to light are used, such as a photosensitive pressure-sensitive recording medium as disclosed in U.S. Pat. No. 4,399,209 to Sanders et al, the amount of light emitted from the light source needs to be increased even if the recording is performed under a normal density mode. If it is required that the recording be performed under a high density mode, the amount of light emitted from the light source must further be increased. This shortens the service life of the light source and incurs serious problems, i.e. an increased amount of heat generation and an increased amount of current consumption.